Flux composition and method for treating uranium-containing metal



United Stats FLUX COMPOSITION AND MET H 313 FOR TREAT- ING URANIUM-CONTAINING METAL Frank Foote, Chicago, 111., assignor to the United States of America as represented by the United States Atomic Energy Commission No Drawing. Application December 3, 1945 Serial No. 632,598

3 Claims. (Cl. 75--84.1)

The present invention relates to protective fluxes and is particularly concerned with providing protective fluxes for the melting of uranium and alloys of uranium.

In the past, several fluxes or mixtures of flux materials have been used for the protection of molten metals in order to prevent surface oxidation or to hinder the volatilization of low-melting metals during alloying processes. Certain fundamental requisites must be met by this type of flux. For example, it must have a melting point considerably below that of the metal and its alloys. At the same time the flux must have the proper specific gravity and surface tension in order to float on the metal or alloy when in molten condition and at the same time to cover the same with a substantially inert protective layer in order to prevent undue oxidation thereof, and also to prevent volatilization of the metal and its alloys. In addition there must, of course, be no chemical reaction between the flux and the metal or its alloys. Very few fluxes meet all of the foregoing requirements, the majority being ruled out because they react with the metal or do not have the required combination of specific gravity and surface tension to prevent surface oxidation or volatilization. The problem of securing a suitable protective flux is particularly diflicult when highly reactive metals, such as uranium, are to be protected.

I have discovered a new flux which is particularly adapted for use in the melting of uranium and its alloys. especially those alloys in which uranium is the predominant component.

The flux which I have found suitable to employ for the purposes above-mentioned is compounded in such manner that is possesses the following physical properties:

(1) It is fluid at temperatures below the melting point of uranium and commercial uranium alloys, i. e. it melts at approximately 1000-1100 C.; and

(2) It has a lower specific gravity when fluid than molten uranium or commercial uranium alloys.

I have found that a flux having such properties can be prepared by admixing in suitable proportions calcium fluoride, calcium chloride and uranium tetrafluoride. I have discovered that proportions of the various ingredients in this flux may be varied somewhat without substantially changing the desirable characteristics of my new and novel flux. I have found that the composition of a suitable flux, calculated on an anhydrous basis, may vary from about 50 percent to 70 percent by weight calcium fluoride, 20 percent to 40 percent by weight calcium chloride, and 5 percent to 15 percent by weight uranium tetrafluoride.

As a specific example of the preparation of a suitable flux and its use in preparing uranium-lead alloys, approximately percent by weight of calcium fluoride 30 percent by weight of calcium chloride and 10 percent by weight of uranium tetrafluoride were thoroughly mixed together. The flux was then placed in a graphite crucible and melted; thereafter uranium metal was charged into the crucible and melted, and then lead was added in an amount suflicient to form the desired alloy. No substantial oxidation of the uranium occurred since the protective flux formed a molten layer resting upon and protecting the molten uranium.

It will be apparent to those skilled in the art to which this invention pertains that various modifications may be made without departing from the principles of the invention as disclosed herein, and thus it is not intended that the invention should be limited other than by the scope of the appended claims.

What is claimed is:

1. A flux composition for use with metals wherein uranium predominates, said flux comprising about 50 percent to percent by weight of calcium fluoride, about 20 percent to 40 percent by weight of calcuim chloride and about 5 percent to 15 percent by weight of uranium tetrafluoride.

2. A flux composition for use with molten uranium and alloys thereof wherein uranium predominates, said flux comprising about 60 percent by weight of calcium fluoride, about 30 percent by weight of calcium chloride and about 10 percent by weight of uranium tetrafluoride.

3. In a method of melting uranium and uranium base alloys the step of adding a flux comprising about 50 to 70 percent by weight of calcium fluoride, about 20 to 40 percent by weight of calcium chloride and about 5 to 15 percent by weight of uranium tetrafluoride.

References Cited in the file of this patent UNITED STATES PATENTS 1,673,043 Fischer June 12, 1928 2,040,283 Swartz May 12, 1936 2,051,963 Monroe et al Aug. 25, 1936 2,327,065 Reimers Aug. 17, 1943 

1. A FLUX COMPOSITION FOR USE WITH METALS WHEREIN URANIUM PREDOMINATES, SAID FLUX COMPRISISNG ABOUT 50 PERCENT TO 70 PERCENT BY WEIGHT OF CALCIUM FLUORIDE, ABOUT 20 PERCENT TO 40 PERCENT BY WEIGHT OF CALCIUM CHLORIDE AND ABOUT 5 PERCENT TO 15 PERCENT BY WEIGHT OF URANIUM TETRAFLUORIDE.
 3. IN A METHOD OF MELTING URANIUM AND URANIUM BASE ALLOYS THE STEP OF ADDING A FLUX COMPRISING ABOUT 50 TO 70 PERCENT BY WEIGHT OF CALCIUM FLUORIDE, ABOUT 20 TO 40 PERCENT BY WEIGHT OF CALCIUM CHLORIDE AND ABOUT 5 TO 15 PERCENT BY WEIGHT OF URANIUM TETRAFLUORIDE. 